Field of Invention
The present invention belongs to a technical field of optical communication, relates to a preparation technology and an application of an optical communication LED (Light Emitting Diode), and more particularly to a light-responsive LED based on a GaN/CsPbBrxI3-x heterojunction, a preparation method and an application thereof.
Description of Related Arts
The visible light wireless communication is known as the LiFi (Light Fidelity) technology, which is a wireless transmission technology for data transmission with utilizing the spectrums of visible light (such as light emitted by the bulb) and is invented by Harald Hass who is the chairman of mobile communication department of electro-communication college of England Edinburgh University and is a physicist. Because of advantages of high rate, no electromagnetic radiation, high density, low cost, rich spectrums and high confidentiality, the LiFi technology is regarded as the next-generation wireless communication technology after WiFi and gains a lot of attentions.
Currently, the LiFi technology has a difficult problem required to be urgently solved, namely the backward communication. The communication from the signal source to the mobile phone is defined as the forward communication, and the communication from the mobile phone to the signal source is the backward communication. The current situation is that the forward communication is easily solved. With the LED as the signal source, the forward communication can be easily realized through adding a photoelectric detector as the receiving terminal on the mobile phone. However, the common photoelectric detector does not have the luminescent property, and the LED does not have the optical detection ability, so that the backward communication cannot be realized. The LED transmits the signal and the photoelectric detector on the mobile phone receives the signal, which only solves half of the problem; only when the signal is able to be transmitted back from the mobile phone, the communication link is ensured to be smooth. That is to say, if the backward communication cannot be effectively solved, the terminal devices such as the mobile phone can only download the data, but cannot update the data, which undoubtedly restricts the development of the LiFi technology. Thus, developing a device having double functions of optical detection and electroluminescence to realize the forward and backward communication of the LiFi technology is a technical problem required to be urgently solved by researchers in field.
In 2017, oh et al. reported a device integrated with double functions of photoelectric detector and light emitting diode[1] on Science. In the report, the great application prospect of the di-functional device was showed, especially the applications in fields of screen luminance control and information communication. Since then, the di-functional device has aroused interests of the researchers. Moreover, in recent years, the halogen family perovskite has showed extraordinary performance in the photoelectric field and is widely applied in the solar cell, photoelectric detector and light emitting diode[2-4]. Among the halogen family perovskite, because of the high stability, the all-inorganic perovskite CsPbBr3 overcomes the shortcomings that the organic-inorganic hybridized perovskite is difficult to be preserved in the atmospheric environment and easily decomposed when heated, and is widely applied in the light emitting diode or photoelectric detector[5-6]. Thus, the high-performance device may be prepared if applying the all-inorganic perovskite CsPbBr3 in the di-functional integrated device.
Conventionally, CsPbBr3 as the luminescent layer is applied in the light emitting diode in forms of three-dimensional polycrystalline film, two-dimensional nanosheet and zero-dimensional quantum dot[7-9]. However, the two-dimensional nanosheet and the zero-dimensional quantum dot have strong quantum restriction effects, which is disadvantageous for exciton separation to realize the optical detection. Moreover, in the previous reports, the thickness and discontinuity of the three-dimensional CsPbBr3 polycrystalline films are problems. To solve the above problems, the present invention devotes to research the preparation method of the three-dimensional CsPbBr3 polycrystalline films, the di-functional devices of photoelectric detection and electroluminescence and its application in visible light wireless communication.